aac
Version:
An AAC decoder for Aurora.js
197 lines (171 loc) • 5.88 kB
JavaScript
/*
* AAC.js - Advanced Audio Coding decoder in JavaScript
* Created by Devon Govett
* Copyright (c) 2012, Official.fm Labs
*
* AAC.js is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 3 of the
* License, or (at your option) any later version.
*
* AAC.js is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
* Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library.
* If not, see <http://www.gnu.org/licenses/>.
*/
/********************************************************************************
* Sample offset into the window indicating the beginning of a scalefactor
* window band
*
* scalefactor window band - term for scalefactor bands within a window,
* given in Table 4.110 to Table 4.128.
*
* scalefactor band - a set of spectral coefficients which are scaled by one
* scalefactor. In case of EIGHT_SHORT_SEQUENCE and grouping a scalefactor band
* may contain several scalefactor window bands of corresponding frequency. For
* all other window_sequences scalefactor bands and scalefactor window bands are
* identical.
*******************************************************************************/
const SWB_OFFSET_1024_96 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 28,
32, 36, 40, 44, 48, 52, 56, 64,
72, 80, 88, 96, 108, 120, 132, 144,
156, 172, 188, 212, 240, 276, 320, 384,
448, 512, 576, 640, 704, 768, 832, 896,
960, 1024
]);
const SWB_OFFSET_128_96 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 32, 40, 48, 64, 92, 128
]);
const SWB_OFFSET_1024_64 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 28,
32, 36, 40, 44, 48, 52, 56, 64,
72, 80, 88, 100, 112, 124, 140, 156,
172, 192, 216, 240, 268, 304, 344, 384,
424, 464, 504, 544, 584, 624, 664, 704,
744, 784, 824, 864, 904, 944, 984, 1024
]);
const SWB_OFFSET_128_64 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 32, 40, 48, 64, 92, 128
]);
const SWB_OFFSET_1024_48 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 28,
32, 36, 40, 48, 56, 64, 72, 80,
88, 96, 108, 120, 132, 144, 160, 176,
196, 216, 240, 264, 292, 320, 352, 384,
416, 448, 480, 512, 544, 576, 608, 640,
672, 704, 736, 768, 800, 832, 864, 896,
928, 1024
]);
const SWB_OFFSET_128_48 = new Uint16Array([
0, 4, 8, 12, 16, 20, 28, 36,
44, 56, 68, 80, 96, 112, 128
]);
const SWB_OFFSET_1024_32 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 28,
32, 36, 40, 48, 56, 64, 72, 80,
88, 96, 108, 120, 132, 144, 160, 176,
196, 216, 240, 264, 292, 320, 352, 384,
416, 448, 480, 512, 544, 576, 608, 640,
672, 704, 736, 768, 800, 832, 864, 896,
928, 960, 992, 1024
]);
const SWB_OFFSET_1024_24 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 28,
32, 36, 40, 44, 52, 60, 68, 76,
84, 92, 100, 108, 116, 124, 136, 148,
160, 172, 188, 204, 220, 240, 260, 284,
308, 336, 364, 396, 432, 468, 508, 552,
600, 652, 704, 768, 832, 896, 960, 1024
]);
const SWB_OFFSET_128_24 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 28,
36, 44, 52, 64, 76, 92, 108, 128
]);
const SWB_OFFSET_1024_16 = new Uint16Array([
0, 8, 16, 24, 32, 40, 48, 56,
64, 72, 80, 88, 100, 112, 124, 136,
148, 160, 172, 184, 196, 212, 228, 244,
260, 280, 300, 320, 344, 368, 396, 424,
456, 492, 532, 572, 616, 664, 716, 772,
832, 896, 960, 1024
]);
const SWB_OFFSET_128_16 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 28,
32, 40, 48, 60, 72, 88, 108, 128
]);
const SWB_OFFSET_1024_8 = new Uint16Array([
0, 12, 24, 36, 48, 60, 72, 84,
96, 108, 120, 132, 144, 156, 172, 188,
204, 220, 236, 252, 268, 288, 308, 328,
348, 372, 396, 420, 448, 476, 508, 544,
580, 620, 664, 712, 764, 820, 880, 944,
1024
]);
const SWB_OFFSET_128_8 = new Uint16Array([
0, 4, 8, 12, 16, 20, 24, 28,
36, 44, 52, 60, 72, 88, 108, 128
]);
exports.SWB_OFFSET_1024 = [
SWB_OFFSET_1024_96,
SWB_OFFSET_1024_96,
SWB_OFFSET_1024_64,
SWB_OFFSET_1024_48,
SWB_OFFSET_1024_48,
SWB_OFFSET_1024_32,
SWB_OFFSET_1024_24,
SWB_OFFSET_1024_24,
SWB_OFFSET_1024_16,
SWB_OFFSET_1024_16,
SWB_OFFSET_1024_16,
SWB_OFFSET_1024_8
];
exports.SWB_OFFSET_128 = [
SWB_OFFSET_128_96,
SWB_OFFSET_128_96,
SWB_OFFSET_128_64,
SWB_OFFSET_128_48,
SWB_OFFSET_128_48,
SWB_OFFSET_128_48,
SWB_OFFSET_128_24,
SWB_OFFSET_128_24,
SWB_OFFSET_128_16,
SWB_OFFSET_128_16,
SWB_OFFSET_128_16,
SWB_OFFSET_128_8
];
exports.SWB_SHORT_WINDOW_COUNT = new Uint8Array([
12, 12, 12, 14, 14, 14, 15, 15, 15, 15, 15, 15
]);
exports.SWB_LONG_WINDOW_COUNT = new Uint8Array([
41, 41, 47, 49, 49, 51, 47, 47, 43, 43, 43, 40
]);
/*
* Scalefactor lookup table
*/
exports.SCALEFACTOR_TABLE = (function() {
var table = new Float32Array(428);
for (var i = 0; i < 428; i++) {
table[i] = Math.pow(2, (i - 200) / 4);
}
return table;
})();
/**
* Inverse quantization lookup table
*/
exports.IQ_TABLE = (function() {
var table = new Float32Array(8191),
four_thirds = 4/3;
for (var i = 0; i < 8191; i++) {
table[i] = Math.pow(i, four_thirds);
}
return table;
})();
exports.SAMPLE_RATES = new Int32Array([
96000, 88200, 64000, 48000, 44100, 32000,
24000, 22050, 16000, 12000, 11025, 8000, 7350
]);